KR20070038962A - Power unit - Google Patents

Abstract

In a power supply apparatus such as a boost or step-down circuit using a switching regulator, a short circuit of the load circuit connected to the output terminal is detected to prevent the large current of the load circuit from flowing. The power supply device 100 includes a switching regulator 30, a regulator 32, a control circuit 34, and a short circuit detection circuit 36. The short circuit detection circuit 36 includes a voltage comparator 20 and a voltage comparator 22, a constant current source 24, a switch SW3, and a short circuit detection capacitor Cx. When Vout <Vth, the switch SW3 is turned on, and the voltage Vx of the short-circuit detection capacitor Cx is charged by the current Ix supplied from the constant current source 24, and slopes with the passage of time. Continue rising to (Ix / Cx). When the voltage Vx becomes higher than the shutdown voltage Vsd, the voltage comparator 22 outputs a high level to the enable terminal EN of the driver circuit 10 and stops the boosting operation of the switching regulator 30.

Description

Power unit {POWER SOURCE DEVICE}

TECHNICAL FIELD This invention relates to a power supply device. Specifically, It is related with the short circuit protection of the power supply device using a switching element.

In a small information terminal operating in a battery such as a portable CD player, a digital still camera, a mobile phone, and the like in recent years, the circuit used therein is limited to requiring the battery voltage itself as a power supply voltage. I never do that. That is, a circuit used inside the small information terminal may require a voltage higher than the battery voltage or, conversely, a voltage lower than the battery voltage. In this case, in order to obtain a desired voltage, the battery voltage is boosted or lowered by a switching regulator or the like to supply an appropriate power supply voltage to each circuit.

By the way, in a small information terminal, the load circuit connected to the output terminal of a power supply device may short circuit for some reason at the time of manufacture of a product, or after shipment. In such a case, if the power supply device continues the step-up operation to output a desired voltage, since a large current continues to flow through the load circuit, there is a concern that the heat generation may affect the reliability of the entire circuit. Therefore, in such a power supply device, a technique for detecting a short circuit in a load circuit and short circuit protection is required. The technique of performing short circuit protection in a power supply device is proposed by patent document 1, for example.

Patent Document 1: Japanese Patent Laid-Open No. 6-311734

This invention aims at providing the short circuit protection by providing the means which detects the short circuit of a load circuit similarly to the technique described in the said literature, but intends to solve the subject by the method different from the technique described in the said literature. An object of the present invention is to provide a power supply device having a short circuit protection function for detecting a short circuit in a load circuit and protecting the circuit.

In order to solve the above problems, a power supply device of one embodiment of the present invention includes a voltage generation circuit having a switching element, a control circuit for controlling the switching operation of the switching element, an output voltage and a predetermined test voltage of the voltage generation circuit. And a voltage comparator to be compared and a timer circuit that becomes active when the output voltage of the voltage generating circuit is lower than the test voltage and measures elapsed time. The control circuit stops the switching operation of the switching element when the elapsed time measured by the timer circuit exceeds a predetermined time.

A "voltage generating circuit having a switching element" refers to a circuit which generates a desired voltage by turning on / off a switch and performing energy conversion using a capacitor or an inductor, and boosting by a switching regulator or a switched capacitor method. , Step-down, voltage inversion circuits, and the like.

When the load circuit is short-circuited, the output voltage continues to be lower than the predetermined test voltage. Therefore, the timer circuit measures the time when the output voltage is lower than the predetermined test voltage and compares it with the predetermined time, whereby it is possible to determine whether or not there is a short circuit in the load circuit.

The timer circuit may include a capacitor having one end grounded, a constant current source connected to the other end of the capacitor, a voltage comparator for comparing the voltage at the other end of the capacitor with a predetermined reference voltage. The elapsed time measured by the timer circuit may correspond to the voltage at the other end of the capacitor charged by the constant current source, and the predetermined time may correspond to the predetermined reference voltage.

By charging the capacitor by the constant current source, since the voltage is output in proportion to the time from the capacitor, the time can be converted into a voltage. By comparing this voltage with a predetermined voltage, the passage of a predetermined time can be detected.

Another embodiment of the present invention is also a power supply device. The power supply apparatus includes a voltage generating circuit having a switching element, a control circuit for controlling a switching operation of the switching element, a timer circuit for outputting a signal of a predetermined level when a predetermined time elapses from the start of the switching operation, and a timer circuit. It is activated when a signal of a predetermined level is output, and has a voltage comparator for comparing the output voltage of the voltage generating circuit with a predetermined inspection voltage. The control circuit stops the switching operation of the switching element when the output voltage of the voltage generation circuit is lower than the test voltage.

According to this aspect, when the time is measured by a timer circuit and the output voltage does not reach the predetermined voltage after a predetermined time has elapsed, it is determined that the load circuit is short-circuited, and the switching operation of the switching element is stopped to load Supply of current to the circuit can be stopped.

The timer circuit includes a capacitor having one end grounded, a constant current source connected to the other end of the capacitor, a voltage comparator for comparing the voltage at the other end of the capacitor with a predetermined voltage, and when the voltage at the other end of the capacitor becomes higher than the predetermined voltage. The signal of a predetermined level may be output.

According to this aspect, since the capacitor is charged by the constant current source, since the voltage is output in proportion to the time from the capacitor, the time can be converted into a voltage. By comparing this voltage with a predetermined voltage, a predetermined time can be measured.

The control circuit may perform the switching operation of the switching element at a predetermined fixed duty during the predetermined startup period from the start of the switching operation.

In this case, if a short circuit of the load circuit is not detected during the startup period, the output voltage of the voltage generation circuit can be raised. Moreover, when a short circuit is detected, since a switching operation is stopped, a switching element is driven by fixed duty and it can prevent that a current flows to a load circuit continuously.

The control circuit may stop the switching operation of the switching element and stop the load circuit connected to the output terminal of the voltage generator circuit.

By stopping the operation of the load circuit in accordance with the stop of switching of the voltage generation circuit, the current flowing from the voltage generation circuit can be reduced, and heat generation of the circuit can be more suitably suppressed.

As described above, in the present invention, 1. The time until the output voltage does not reach the predetermined voltage after the lapse of a predetermined time from the start of the power supply device, or 2. The time until the output voltage reaches the predetermined voltage is determined. It measures and determines that a load circuit is detected in either case when the time is too long.

Further, any combination of the above components, or mutual substitution of a component or expression of the present invention between a method, an apparatus, a system, and the like is also effective as an aspect of the present invention.

By the power supply device according to the present invention, the circuit can be protected.

1 is a circuit diagram showing a power supply device according to an embodiment of the present invention;

2 (a) and 2 (b) are diagrams showing the operation in normal time when the load circuit connected to the output terminal of the power supply device of FIG. 1 is not short-circuited;

3 (a) and 3 (b) show an operation when an abnormality occurs in a load circuit connected to the output terminal of the power supply device of FIG. 1;

4 is a diagram showing a modification of the short circuit detection circuit of FIG. 1;

FIG. 5 is a block diagram illustrating a configuration of an electronic device on which the power supply device of FIG. 1 is mounted.

<Explanation of symbols for main parts of drawing>

SW1: main switch SW2: synchronous rectification switch

SW3: Switch Co: Output Capacitor

Cx: short circuit detection capacitor 10: driver circuit

12: voltage comparator 14: oscillator

16: starter circuit 18: error amplifier

20: voltage comparator 22: voltage comparator

24: constant current source 26 timer circuit

30: switching regulator 32: regulator

34: control circuit 36: short circuit detection circuit

40: short circuit detection circuit 100: power supply

1 is a circuit diagram showing a power supply device 100 according to an embodiment of the present invention. The power supply device 100 is a synchronous rectification type boost converter, which boosts the voltage input to the input terminal 102 by the switching regulator and outputs it to the output terminal 104.

The power supply device 100 includes an input terminal 102, an output terminal 104, and a reference voltage terminal 106. An input voltage Vin is applied to the input terminal 102. The reference voltage terminal 106 is input with a reference voltage Vref for adjusting the output voltage Vout to be output from the output terminal 104. The power supply device 100 may generate a reference voltage Vref therein.

FIG. 5 is a block diagram showing the configuration of an electronic device 300 on which the power supply device 100 of FIG. 1 is mounted. The electronic device 300 is a battery-driven portable device such as a portable CD player, a digital still camera, a mobile phone terminal, and includes a battery 310, a power supply device 100, and a load 320. The battery 310 is a lithium ion battery or the like, and generates a battery voltage Vbat of about 3 to 4 V and outputs it to the input terminal 102 of the power supply device 100. That is, the battery voltage Vbat is the input voltage Vin of FIG. 1. In addition, a load circuit 320 is connected to the output terminal 104 of the power supply device 100. The load circuit 320 is, for example, a device that requires a voltage higher than the battery voltage Vbat such as a light emitting diode (LED) or a charge coupled device (CCD).

Return to FIG. This power supply device 100 includes a switching regulator 30, a regulator 32, a control circuit 34, and a short circuit detection circuit 36. The regulator 32, the control circuit 34, and the short circuit detection circuit 36 are integrated as a functional IC on one semiconductor substrate.

The switching regulator 30 is a general synchronous rectification boost converter, and includes an inductor L1, a main switch SW1, a synchronous rectification switch SW2, and an output capacitor Co. By switching on / off the main switch SW1 and the synchronous rectification switch SW2 alternately, the input voltage Vin is boosted and the output voltage Vout is output to the output terminal 104. The main switch SW1 and the synchronous rectification switch SW2 are metal oxide semiconductor field effect transistors (MOSFETs), and are turned on and off by voltages input to respective gate terminals.

The regulator 32 is a circuit for stabilizing the output voltage Vout based on the reference voltage Vref input to the reference voltage terminal 106. The regulator 32 includes resistors R1 and R2 and an error amplifier 18. Include. The error amplifier 18 includes a non-inverting input terminal and an inverting input terminal, and adjusts the error voltage Verr as its output so that the values of both input terminals are the same. The output voltage Vout is divided by the resistor R1 and the resistor R2 into the inverting input terminal of the error amplifier 18, and fed back as Vout x R1 / (R1 + R2). The reference voltage Vref is applied to the non-inverting input terminal of the error amplifier 18. Therefore, the regulator 32 is fed back such that Vout = Vref x (R1 + R2) / R1 is established between the output voltage Vout and the reference voltage Vref, so that the output voltage Vout is stabilized.

The control circuit 34 generates a switching signal for turning on / off the switching element of the switching regulator 30 based on the error voltage Verr output from the regulator 32. This control circuit 34 includes an oscillator 14, a starter circuit 16, a voltage comparator 12, and a driver circuit 10. The oscillator 14 generates a triangular or sawtooth-shaped periodic voltage Vosc at a constant frequency. The starter circuit 16 is a circuit used at startup and outputs a start voltage Vst for turning on and off the switches SW1 and SW2 of the switching regulator 30 with a fixed duty.

The voltage comparator 12 compares the start voltage Vst output from the starter circuit 16 and the periodic voltage Vosc output from the oscillator 14 during the start-up period of the power supply device 100, and Vst> Vosc. Outputs a pulse width modulated signal (hereinafter referred to as PWM signal Vpwm) that becomes a high level. In addition, the voltage comparator 12 compares the error voltage Verr outputted from the regulator 32 and the periodic voltage Vosc after the startup is completed, and the PWM signal Vpwm which becomes a high level when Verr> Vosc. ) The duty ratio of the PWM signal Vpwm generated in this way is fixed at startup, and changes according to the error voltage Verr after completion of startup.

The driver circuit 10 is a circuit for alternately turning on / off the main switch SW1 and the synchronous rectification switch SW2 based on the PWM signal Vpwm. Two switching signals are output from the driver circuit 10, and the respective signals are input to the gate terminals of the main switch SW1 and the synchronous rectification switch SW2, thereby controlling the switching operation. During the period when the PWM signal Vpwm is at the low level, the main switch SW1 is turned on, and the synchronous rectification switch SW2 is turned off. On the contrary, during the period when the PWM signal Vpwm is at the high level, the main switch SW1 is turned off and the synchronous rectification switch SW2 is turned on. When the main switch SW1 is turned on, current flows through the inductor L1 and the main switch SW1, and energy is stored in the inductor L1. When the synchronous rectification switch SW2 is turned on, current flowing in the inductor L1 while the main switch SW1 is turned on flows into the output capacitor Co through the synchronous rectification switch SW2. The main switch SW1 and the synchronous rectification switch SW2 are alternately turned on and off in accordance with the duty of the PWM signal Vpwm, and the output voltage 104 is boosted to smooth the input voltage Vin. The output voltage Vout is output.

In addition, the driver circuit 10 includes an enable terminal EN. When a high level is input to the enable terminal EN, the two switching signals are fixed to the ground potential to fix the main switch SW1 and the synchronous rectification. The switching operation of the switching switch SW2 is stopped, and the boosting operation of the switching regulator 30 is stopped.

The PWM signal Vpwm for controlling the on / off of the main switch SW1 and the synchronous rectification switch SW2 of the switching regulator 30 is based on the error voltage Verr obtained by feeding back the output voltage Vout. Since it is determined, the output voltage Vout is maintained at a constant value determined by the reference voltage Vref.

Hereinafter, the structure of the short circuit detection circuit 36 which is a characteristic part of the power supply device 100 which concerns on this embodiment is demonstrated. The short circuit detection circuit 36 is a circuit for detecting a short circuit of the load circuit connected to the output terminal 104 of the power supply device 100 and includes a voltage comparator 20 and a timer circuit 26.

The voltage comparator 20 compares the output voltage Vout with a predetermined test voltage Vth, outputs a high level when Vth> Vout, and outputs a low level when Vth <Vout.

The timer circuit 26 includes a voltage comparator 22, a constant current source 24, a switch SW3, and a short circuit detection capacitor Cx, and the output voltage Vout of the voltage generation circuit 30 is a test voltage. When it is lower than (Vth), it becomes active and the elapsed time is measured. The timer circuit 26 outputs the high level stop signal SIG1 when the measured time exceeds the predetermined time.

The constant current source 24 sends a current having a constant current value Ix to the short circuit detecting capacitor Cx through the switch SW3. One end of the short circuit detection capacitor Cx is grounded, and the other end thereof is connected to the constant current source 24 via the switch SW3. The short circuit detection capacitor Cx is charged by the constant current Ix supplied by the constant current source 24, and the voltage Vx of the short circuit detection capacitor Cx during the period in which the switch SW3 is turned on. ) Is a voltage proportional to time. The timer circuit 26 configured as described above becomes active when the switch SW3 is on and measures time.

Shutdown voltage Vsd and voltage Vx are input to voltage comparator 22. The voltage comparator 22 compares two input voltages, and when the voltage Vx becomes greater than the shutdown voltage Vsd, the voltage comparator 22 has a high level at the enable terminal EN of the driver circuit 10 of the control circuit 34. Output the stop signal SIG1.

The output of the voltage comparator 20 is input to the switch SW3. The switch SW3 is turned on when the high level is input and turned off when the low level is input. The switch SW3 can be configured by a MOSFET, a bipolar transistor, or the like, and can be turned on / off by changing the gate voltage or the base voltage.

The short circuit detection circuit 36 configured in this manner measures a time when the output voltage Vout is lower than the detection voltage Vth, and determines that the load circuit is in a short circuit state when this time exceeds a predetermined time, and thus the high level. Outputs a stop signal SIG1.

The stop signal SIG1 is input to the enable terminal EN of the driver circuit 10. As described above, the driver circuit 10 stops the switching operation of the main switch SW1 and the synchronous rectification switch SW2 when a high level is input to the enable terminal EN. In this way, the control circuit 34 stops the switching operation of the switching element when the elapsed time measured by the timer circuit 26 exceeds a predetermined time.

The operation of the power supply device 100 configured as described above will be described based on Figs. 2 (a), (b) and 3 (a) and (b). 2 (a) and 2 (b) are diagrams showing the operation in normal time when the load circuit connected to the output terminal 104 of the power supply device 100 is not shorted. 3 (a) and 3 (b) are diagrams showing an operation during abnormality when the load circuit connected to the output terminal 104 of the power supply device 100 is short-circuited.

First, with reference to Figs. 2 (a) and 2 (b), the operation in normal time when the load circuit is not short-circuited will be described.

The boosting operation of the power supply device 100 is started at time T0. In the period of time T0-T1, the output of the starter circuit 16 used at the time of starting of the power supply device 100 becomes active, and the output voltage Vout is stepped up by fixed duty until time T1.

When the output voltage Vout> V1 is reached, the output of the starter circuit 16 is turned off, and the error voltage Verr of the error amplifier 18 is adjusted so that Vout = (R1 + R2) / R2 x Vref as described above. Based on the error voltage Verr, the PWM comparator 12 generates the PWM signal Vpwm. The driver circuit 10 turns on / off the main switch SW1 and the synchronous rectification switch SW2 in accordance with the duty of the PWM signal Vpwm, thereby boosting the input voltage Vin to a desired voltage. By adjusting the error voltage Verr by feedback, the output voltage Vout approaches the voltage given by (R1 + R2) / R2 x Vref.

The short circuit detection circuit 36 has performed the following operations. In Fig. 2A, the times T0 to T1 are starting periods, and the output voltage Vout is boosted to a fixed duty and gradually increases. In the meantime, since the voltage comparator 20 holds Vth &gt; Vout, the switch SW3 is turned on. As the switch SW3 is turned on, the short circuit detection capacitor Cx is charged by the current Ix supplied from the constant current source 24, and the voltage Vx gradually rises with time. When the elapsed time after the charging by the constant current source 24 is started is set to tx, the voltage Vx of the short circuit detection capacitor Cx is given as Vx = Ix / Cx × tx and increases in proportion to the time. Goes.

When the output voltage Vout becomes larger than the test voltage Vth at time T2, the switch SW3 is turned off, and the current supply from the constant current source 24 is cut off. At this time, since charging of the short circuit detection capacitor Cx stops, the voltage Vx takes a fixed value. Thereafter, since the voltage Vx does not rise, it is always smaller than the shutdown voltage Vsd by the voltage comparison in the voltage comparator 22, and a low level is input to the enable terminal EN of the driver circuit 10. Therefore, the boosting operation in the switching regulator 30 is not stopped. When the start-up period ends at time T1, the starter circuit 16 becomes inactive, and the PWM signal Vpwm is generated based on the error voltage Verr output from the regulator 32, and the output voltage (Vout) approaches the desired voltage value.

Next, an operation when the load circuit connected to the output terminal 104 of the power supply device 100 is short-circuited will be described with reference to FIGS. 3A and 3B.

The boosting operation of the power supply device 100 is started at time TO. At time T0, the output of the starter circuit 16 used at the start of the boost operation is activated, the switching of the switching regulator 30 is controlled at a fixed duty, and the boost operation for raising the output voltage Vout is started. do. However, at this time, since the load circuit connected to the output terminal 104 of the power supply device 100 is short-circuited, as shown in FIG. 3 (a), the output voltage Vout does not become larger than a certain value near 0V. Do not.

As a result, the short circuit detection circuit 36 performs the following operations. Since the switch SW3 is continuously turned on when Vout <Vth, the voltage Vx of the short circuit detection capacitor Cx is charged by the current Ix supplied from the constant current source 24, and Ix / Cx. Continues to rise as the slope of. After a while, the voltage Vx of the short circuit detection capacitor Cx becomes larger than the shutdown voltage Vsd at time T3. This time T3 is given by T3 = Vsd / Ix × Cx. In the voltage comparator 22, when Vsd &lt; Vx at time T3, a high level is input to the enable terminal EN of the driver circuit 10, and the step-up operation of the switching regulator 30 is stopped. The stop of the boost operation can be performed by lowering both switching signals output from the driver circuit 10 to the ground potential.

When the boosting operation of the switching regulator 30 is stopped at time T3, the supply of charge to the output capacitor Co is stopped and only discharged to the load circuit, so the output voltage Vout drops to near the ground potential, A large current can be prevented from flowing in the circuit.

At this time, the operation of the load circuit connected to the output terminal 104 may also be stopped. By stopping the operation of the load circuit, the current flowing from the power supply device 100 can be reduced, and heat generation of the circuit can be more effectively suppressed.

In addition, when this power supply device 100 is mounted in a set, a signal informing the short circuit of the load circuit may be output to the circuit which collectively controls the set. If it is a test at the time of manufacture of a set, this signal enables a manufacturer to detect the short circuit of a load circuit before shipment, and can perform a cause analysis etc., for example. In addition, even after the shipment of the set, the circuit that collectively controls the set can perform appropriate processing such as informing the user of the failure.

As described above, in the power supply device 100 according to the present embodiment, the short circuit of the load circuit is detected by the short circuit detection circuit 36 to detect the main switch SW1 and the synchronous rectification switch SW2 of the switching regulator 30. By turning off all of them, the switching operation is stopped, the current supply to the load circuit is interrupted, and a large current can be prevented from flowing.

As shown in Figs. 2A and 2B, when a short circuit abnormality does not occur in the load circuit, the operation of the switching regulator 30 is not affected.

It is to be understood by those skilled in the art that the above embodiments are illustrative and that various modifications can be made to the combinations of these components and the respective treatment processes, and that such modifications are also within the scope of the present invention.

For example, the short circuit detection circuit 36 used in this embodiment may be replaced by the short circuit detection circuit 40 shown in FIG. The short circuit detection circuit 40 determines that the load circuit is short-circuited when the output voltage Vout has not reached the predetermined test voltage Vth after a lapse of time from the start of the power supply device 100. .

The short circuit detection circuit 40 includes a timer circuit 26 and a voltage comparator 44. The configuration of the timer circuit 26 is the same as that in FIG. The short circuit detection capacitor Cx is charged by the constant current Ix supplied by the constant current source 24, and the voltage Vx of the short circuit detection capacitor Cx during the period in which the switch SW3 is turned on. Functions as a timer circuit that rises with time. The on / off of the switch SW3 is controlled by the reference voltage Vref, and the switch SW3 is turned on when the reference voltage Vref of a predetermined value or more is input. The timer circuit 26 becomes active for a period when the switch SW3 is on and starts time measurement.

The voltage comparator 42 inputs the voltage Vx and the voltage Vtime of the short circuit detection capacitor Cx. When the short circuit detection capacitor Cx is charged and Vx &gt; Vtime, the voltage comparator 42 outputs a high level signal. When the switch SW3 is turned on by inputting the reference voltage Vref simultaneously with the start of the boost operation, the timer circuit 26 outputs a signal of a predetermined level when a predetermined time elapses from the start of the switching operation. The output of this voltage comparator 42 is input to the voltage comparator 44. That is, this timer circuit 26 measures the fixed time determined by the voltage Vtime, and notifies the voltage comparator 44 of the passage of the time.

The voltage comparator 44 performs the voltage comparison operation only when the output of the voltage comparator 42 has reached a predetermined level, that is, a high level. The output voltage Vout of the power supply device 100 and the test voltage Vth are input to the voltage comparator 44, and when Vout <Vth, the output is made high. The output of the voltage comparator 44 is connected to the enable terminal EN of the driver circuit 10 of FIG. 1. Therefore, when the high level is output from the timer circuit 26, the control circuit 34 has the main switch SW1 when the output voltage Vout of the voltage generation circuit 30 is lower than the test voltage Vth. , The switching operation of the synchronous rectification switch SW2 is stopped.

If the load circuit of the power supply device 100 is not short-circuited, the output voltage Vout will be larger than any voltage after a predetermined time has elapsed from the start of the boost operation. On the contrary, when the load circuit is short-circuited, the output voltage Vout does not rise, and since Vout <Vth even after a lapse of a predetermined time, a short circuit of the load circuit can be detected. The time at which this voltage is compared can be adjusted by the voltage Vtime, the short circuit detection capacitor Cx, and the constant current Ix.

In this embodiment, an N-type MOSFET is used as the main switch SW1 and the synchronous rectification switch SW2, but the present invention is not limited thereto. If the logic and voltage for driving the gate voltage are changed by the driver circuit 10, it is also possible to use a P-type MOSFET. In addition, other types of transistors such as bipolar transistors may be used instead of the MOSFETs, and what is important is to operate as a switching element. What is necessary is just to decide these selection according to the design specification calculated | required by a power supply device, the semiconductor manufacturing process used, etc.

In the embodiment, the boosting converter of the synchronous rectification type is used as the switching regulator 30, but the present invention is not limited to this, and can be replaced with a power supply circuit having another switching element. The power supply circuit having a switching element is a synchronous rectification switch, and includes a diode rectification switching regulator using a rectifying diode, a boosting circuit using a switched capacitor method, a step-down circuit, a voltage inversion circuit, and the like.

In this embodiment, all the elements which comprise the power supply device 100 may be integrated together, and a part may be comprised by individual components. What part should be integrated depends on cost, an occupied area, etc.

By the power supply device according to the present invention, it is possible to protect the circuit element from short circuit of the load circuit.

Claims (8)

A voltage generation circuit having a switching element, A control circuit for controlling a switching operation of the switching element; A voltage comparator for comparing the output voltage of the voltage generation circuit with a predetermined test voltage; A timer circuit that becomes active when the output voltage of the voltage generation circuit is lower than the check voltage, and measures an elapsed time; And the control circuit stops the switching operation of the switching element when the elapsed time measured by the timer circuit exceeds a predetermined time. A voltage generation circuit having a switching element, A control circuit for controlling a switching operation of the switching element; A timer circuit for outputting a signal of a predetermined level when a predetermined time elapses from the start of the switching operation; A voltage comparator which becomes active when a signal of a predetermined level is output from the timer circuit, and compares an output voltage of the voltage generation circuit with a predetermined inspection voltage, And the control circuit stops the switching operation of the switching element when the output voltage of the voltage generation circuit is lower than the check voltage. The method according to claim 1 or 2, And the control circuit performs a switching operation of the switching element at a predetermined fixed duty during a predetermined startup period from the start of the switching operation. The method according to claim 1 or 2, And the control circuit stops the switching operation of the switching element and stops the operation of the load circuit connected to the output terminal of the voltage generating circuit. The method according to claim 1 or 2, And the control circuit, the voltage comparator, and the timer circuit are integrated on one semiconductor substrate. Battery, An electronic apparatus comprising the power supply device according to claim 1 or 2 for boosting or stepping down a voltage of the battery and outputting the voltage. In the control method of the voltage generation circuit having a switching element, Voltage comparing the output voltage of the voltage generating circuit with a predetermined test voltage; A time measurement step of measuring a period and time during which the output voltage of the voltage generation circuit is lower than the test voltage; And stopping the switching operation of the switching element when the time measured by the time measuring step exceeds a predetermined time. In the control method of the voltage generation circuit having a switching element, Detecting a lapse of a predetermined time from the start of the switching operation of the switching element; When the elapse of the predetermined time is detected, voltage comparing the output voltage of the voltage generation circuit with a predetermined test voltage; Stopping the switching operation of the switching element when the output voltage of the voltage generation circuit is lower than the test voltage as a result of the voltage comparison.

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